a(n) = binomial((n+1)^2, n) / (n+1)^2.

A143669

a(n) = binomial((n+1)^2, n) / (n+1)^2.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =35a(4) =506a(5) =10472a(6) =285384a(7) =9706503a(8) =397089550a(9) =19022318084

External references